Effect of Disodium Cromoglycate on Ventilation and Gas Exchange During Exercise in Asthmatic Children With a Postexertion FEVi Fall Less Than 15 Percent: Cardiorespiratory and Metabolic Monitoring
Respiratory variables were measured by an open-circuit method minute ventilation (Ve, at body temperature, ambient pressure, and saturated with water) and respiratory rate were measured by a 10-L bell spirometer suitable for fast emptying (Biomedin). Oxygen uptake (V02 at temperature 0°C, pressure 760 mm Hg, and dry [O Water vapor]) and carbon dioxide production (Vcc>2, STPD), were determined from the volume and the O2 and CO2 composition of the expired air, collected in a mixing chamber. The O2 concentration was analyzed by a paramagnetic O2 analyzer and CO2 concentration, by an infrared CO2 analyzer (Biomedin).
The Ve (L-min), Vo2 (ml• min • kg), Vco2 (ml-min •kg), respiratory rate, and HR were measured and displayed every 4 s; a computer printed out the averaged 30-s values. We measured the two following parameters of aerobic response to exercise: the peak V02, taken as the highest V02 achieved during the test, and the anaerobic threshold (AT [O2 ml-min-kg]), identified indirectly at the point where hyperventilation with respect to V02 occurred, with an increase in the ventilatory equivalent for V02 (VE/V02) without concomitant increase in the ventilatory equivalent for VCO2 (VE/VCO2) as previously described. The EC of running, ie, the amount of O2 consumed per unit of body mass and running distance (O2 ml-kg *m), was calculated as the ratio of V02 above resting divided by the running speed. The HR was monitored by a cardiofrequency meter (Sport Tester 3000, Polar Kempele, Finland). online antibiotics
Results are expressed as mean ± SD unless otherwise reported. Statistical analysis included the paired Student’s t test to compare the data between the two tests. Analysis of variance (ANOVA [repeated measures]) was used to compare, from rest up to the last minute of the run, the time course of the respiratory variables between the two tests. In order to detect a possible correlation between the degree of airway caliber at the end of exercise and the ventilatory work load, we compared the difference between the FEVi fall of tests A and В and the difference between the maximal minute ventilation (VEmax) in the two tests by a linear regression analysis. The limit for statistical significance was set at a probability value of less than 0.05.